You wouldn't expect your local shop to accept Singapore dollar$ in Barnoldwick would you - therefore you need the currency of the country you are in. Otherwise you will get ripped off with a rubbish exchange rat.
Denmark, Norway, Sweden, Estonia, Latvia , Lithuania and Britain all have their own currency but all except Britain will accept Euros (Exception M & S) although you can expect sometimes to get their own currency in exchange It is hard to get roubles outside Russia and it is best to take good condition US dollars or Euro notes to change once there. It is illegal to pay for goods or services in hard currency, though it is often accepted. Generally speaking with a wallet full of Euros and US Dollars you can travel and pay for things all over the world. Providing you stay with your credit card, don’t let them take it away into the back, it can be useful to use that for purchases and if you use a Nationwide card the exchange rate is excellent….regards Nei.